Advance in cell biology and recombinant protein technologies has led to the development of protein therapeutics.
Yet, major hurdles still exist. Most proteins are susceptible to proteolytic degradation and therefore have a short half-life in the circulating system. Other disadvantages include low water solubility and inducement of neutralizing antibodies.
Attachment of a polymer, e.g., polyethylene glycol (PEG), to a protein hinders access of proteolytic enzymes to the protein backbone, resulting in enhanced protein stability. In addition, it also improves water solubility and minimizes immuogenicity. There is a need for effective methods of attaching a polymer to a protein.